In the area of water treatment, such as ground water or industrial waste water treatment, there is an ever-increasing need to remove undesirable and even toxic contaminants, particularly heavy metal contaminants, from water. Many industrial processes utilize aqueous solutions of heavy metals, such as lead in manufacture of batteries, and chromium or copper in electroplating solutions.
Unfortunately, the removal of such heavy metals from the aqueous solutions used in these processes has proven to be not only difficult but expensive, especially when conducted in batch processing. In order to reduce the cost and time of decontamination, prior art continuous processes have utilized quite expensive synthetic ion-exchange resins packed in a column, through which the contaminated water is passed for treatment and heavy metal removal. Typically, such synthetic ion-exchange resins require reverse flushing of the packed column to regenerate the resin, whereby a heavy metal-contaminated flushing fluid is produced, making disposal still difficult.
U.S. Pat. No. 4,133,755 to Tarao et al., incorporated by reference herein, discloses agents for removing heavy metals comprising a composition consisting mainly of a dithiocarbamate bond-containing low molecular weight compound, amorphous silica and activated carbon powder, granulated with a vinyl acetate polymer binder and clay as a thixotropic excipient. The patentees disclose packing said granulated materials into columns for treating mercury-contaminated waste water.
U.S. Pat. No. 5,667,694 to Cody et al., incorporated by reference herein, discloses a process for removing dissolved heavy metals including lead and radioactive contaminants from contaminated aqueous systems including aqueous soil systems. An organically modified smectite clay, or organoclay, is used to treat these systems. Organoclays are the reaction product of smectite clays and quaternary ammonium compounds. The organoclay is brought in contact with system to be treated where it sorbs the heavy metal in the aqueous system onto the organoclay which sorbed complex is then removed by a variety of methods including flotation and air sparging.
U.S. Pat. No. 5,256,615 to Oomura et al., incorporated by reference herein, discloses a granular inorganic ion exchanger which is obtained by firing at 400° C. or higher a granular molded product of a mixture of a metal alkoxide such as Si(OMe)4 or hydrolyzate thereof, a clay mineral such as sepiolite and an inorganic ion exchanger such as antimony pentoxide and which has mechanical strength and heat resistance without losing its inherent ion exchangeability.
U.S. Pat. No. 5,045,210 to Chen et al., incorporated by reference herein, discloses an ion-exchange media comprising a modified polysaccharide material and a modified particulate polymeric material, said modified materials comprising a polysaccharide and particulate polymeric materials covalently bonded to a synthetic polymer, said synthetic polymer comprising a copolymer made from a polymerization of: (a) a polymerizable compound having a chemical group capable of covalently coupling, directly or indirectly, to said materials; and (b) a polymerizable compound containing (i) an ionizable chemical group or (ii) a chemical group capable of transformation to an ionizable chemical group. The media is useful to selectively remove heavy metal contaminants from aqueous solutions containing said contaminants.
World Patent Publication No. WO 00/72958 to Payzant et al., incorporated by reference herein, discloses a networked polymer/clay alloy produced from a monomer/clay mixture comprising a monomer, a cross-linking agent and clay particles. The clay is chemically integrated with the polymer such that, on exposure to water, the networked polymer/clay alloy swells with substantially no clay separating from the alloy.
However, none of the above-discussed references discloses or suggests a relatively inexpensive but highly effective ion-exchange packing for removal of heavy metal contaminants from contaminated water streams. Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.